Ubuntu – Installing 4.4 rc7 kernel yields i915 module not available

Dears,
I installed the 4.4 rc7 kernel on my ubuntu 15.10 following this page
github.com/awesomebytes/ubuntu14_dell_xps13_9350
just replacing code for rc6 with code for rc7.

when installing I got an error message that i915 was not found, as this seems linked to 3D acceleration, I am a bit worried that I am loosing some performance.
What could/should I do ?

according to first comment I now installed rc8, I still used the same install script as in the link above.

Here is the output

Sélection du paquet linux-headers-4.4.0-040400rc8 précédemment
désélectionné. (Lecture de la base de données... 291800 fichiers et
répertoires déjà installés.) Préparation du dépaquetage de
linux-headers-4.4.0-040400rc8_4.4.0-040400rc8.201601051225_all.deb ...
Dépaquetage de linux-headers-4.4.0-040400rc8
(4.4.0-040400rc8.201601051225) ... Sélection du paquet
linux-headers-4.4.0-040400rc8-generic précédemment désélectionné.
Préparation du dépaquetage de
linux-headers-4.4.0-040400rc8-generic_4.4.0-040400rc8.201601051225_amd64.deb
... Dépaquetage de linux-headers-4.4.0-040400rc8-generic
(4.4.0-040400rc8.201601051225) ... Sélection du paquet
linux-image-4.4.0-040400rc8-generic précédemment désélectionné.
Préparation du dépaquetage de
linux-image-4.4.0-040400rc8-generic_4.4.0-040400rc8.201601051225_amd64.deb
... Done. Dépaquetage de linux-image-4.4.0-040400rc8-generic
(4.4.0-040400rc8.201601051225) ... Paramétrage de
linux-headers-4.4.0-040400rc8 (4.4.0-040400rc8.201601051225) ...
Paramétrage de linux-headers-4.4.0-040400rc8-generic
(4.4.0-040400rc8.201601051225) ... Examining
/etc/kernel/header_postinst.d. run-parts: executing
/etc/kernel/header_postinst.d/dkms 4.4.0-040400rc8-generic
/boot/vmlinuz-4.4.0-040400rc8-generic : Unable to find an initial ram
disk that I know how to handle. Will not try to make an initrd. :
Unable to find an initial ram disk that I know how to handle. Will not
try to make an initrd. Error! Problems with depmod detected. 
Automatically uninstalling this module. DKMS: Install Failed (depmod
problems).  Module rolled back to built state. Paramétrage de
linux-image-4.4.0-040400rc8-generic (4.4.0-040400rc8.201601051225) ...
Running depmod. update-initramfs: deferring update (hook will be
called later) Examining /etc/kernel/postinst.d. run-parts: executing
/etc/kernel/postinst.d/apt-auto-removal 4.4.0-040400rc8-generic
/boot/vmlinuz-4.4.0-040400rc8-generic run-parts: executing
/etc/kernel/postinst.d/dkms 4.4.0-040400rc8-generic
/boot/vmlinuz-4.4.0-040400rc8-generic : Unable to find an initial ram
disk that I know how to handle. Will not try to make an initrd.
run-parts: executing /etc/kernel/postinst.d/initramfs-tools
4.4.0-040400rc8-generic /boot/vmlinuz-4.4.0-040400rc8-generic update-initramfs: Generating /boot/initrd.img-4.4.0-040400rc8-generic
W: Possible missing firmware /lib/firmware/i915/skl_guc_ver4.bin for
module i915 run-parts: executing /etc/kernel/postinst.d/pm-utils
4.4.0-040400rc8-generic /boot/vmlinuz-4.4.0-040400rc8-generic run-parts: executing /etc/kernel/postinst.d/unattended-upgrades
4.4.0-040400rc8-generic /boot/vmlinuz-4.4.0-040400rc8-generic run-parts: executing /etc/kernel/postinst.d/update-notifier
4.4.0-040400rc8-generic /boot/vmlinuz-4.4.0-040400rc8-generic run-parts: executing /etc/kernel/postinst.d/zz-update-grub
4.4.0-040400rc8-generic /boot/vmlinuz-4.4.0-040400rc8-generic Création du fichier de configuration GRUB… Attention : Définir GRUB_TIMEOUT à
une valeur non nulle si GRUB_HIDDEN_TIMEOUT est définie n’est plus
possible. Image Linux trouvée : /boot/vmlinuz-4.4.0-040400rc8-generic
Image mémoire initiale trouvée :
/boot/initrd.img-4.4.0-040400rc8-generic Image Linux trouvée :
/boot/vmlinuz-4.4.0-040400rc7-generic Image mémoire initiale trouvée :
/boot/initrd.img-4.4.0-040400rc7-generic Image Linux trouvée :
/boot/vmlinuz-4.2.0-23-generic Image mémoire initiale trouvée :
/boot/initrd.img-4.2.0-23-generic Image Linux trouvée :
/boot/vmlinuz-4.2.0-22-generic Image mémoire initiale trouvée :
/boot/initrd.img-4.2.0-22-generic Image Linux trouvée :
/boot/vmlinuz-4.2.0-16-generic Image mémoire initiale trouvée :
/boot/initrd.img-4.2.0-16-generic Found memtest86+ image:
/memtest86+.elf Found memtest86+ image: /memtest86+.bin fait

Installing BCM4350 driver Adding initramfs rules to load i915
(graphics) and nvme (SSD) update-initramfs: Generating
/boot/initrd.img-4.4.0-040400rc8-generic W: Possible missing firmware
/lib/firmware/i915/skl_guc_ver4.bin for module i915 update-initramfs:
Generating /boot/initrd.img-4.4.0-040400rc7-generic W: Possible
missing firmware /lib/firmware/i915/skl_guc_ver4.bin for module i915
update-initramfs: Generating /boot/initrd.img-4.2.0-23-generic
update-initramfs: Generating /boot/initrd.img-4.2.0-22-generic
update-initramfs: Generating /boot/initrd.img-4.2.0-16-generic Done,
now you can reboot (maybe you'll need to do it twice).

It seems that the i915 is at the end of the script on this part

sudo bash -c "echo 'i915
nvme' >> /etc/initramfs-tools/modules"
sudo update-initramfs -u -k all

It also yields some more issues before as well, but which seems less of a worry (DKMS is driver for the usb wifi dongle which I don't need anymore).

Thx,
Timothé